1. Field of the Invention
The present invention relates to a production process of a gas turbine for use in various types of gas turbine systems.
2. Description of the Related Art
The exhaust temperature of a gas turbine is as high as about 500° C. As described in, e.g., Journal of Gas Turbine Society of Japan, Vol. 25, No. 97 (1997), therefore, a gas turbine is operated in various cycles, i.e., a combined cycle, a cogeneration cycle, a regenerative cycle, and a high-moisture gas turbine cycle, so as to achieve higher efficiency than that in a simple cycle. In some of those various cycles, the efficiency of an overall system is increased by reducing a pressure ratio from a value at a maximum efficiency point in the simple cycle to raise the exhaust temperature, or by increasing the turbine inlet temperature to raise the exhaust temperature.
Also, in a high-moisture gas turbine cycle disclosed in, e.g., PCT Laid-Open Publication No. WO98/48159, because a turbine is driven with air delivered from a compressor and mixed with moisture, a ratio of turbine capacity to compressor capacity is increased in comparison with those in the other cycles. This necessitates development of a gas turbine dedicated for the high-moisture gas turbine cycle separately from a gas turbine for the simple cycle. Alternatively, as described in a paper (Upgrading of a Small Size Gas Turbine to HAT Cycle Operation: Thermodynamic and Economic Analysis, Umberto Desideri and Francesco di Maria, ASME Paper 99-GT-372, 1999), it is required to constitute the high-moisture gas turbine cycle by combining a compressor used in a relatively small-sized gas turbine and a turbine used in a relatively large-sized gas turbine. Alternatively, as disclosed in Japanese Unexamined Patent Application Publication No. 11-229894, it is required to provide a variable stator vane in a part of a compressor or a turbine so that matching is held between the compressor and the turbine in each of the simple cycle and the high-moisture gas turbine cycle.